Multisensor probe for tissue identification

ABSTRACT

A multisensor probe for continuous real-time tissue identification. The multisensor probe includes a tissue penetrating needle, a plurality of sensors useful in characterizing tissue and a position sensor to measure the depth of the needle into the tissue being diagnosed. The sensors include but are not limited to an optical scattering and absorption spectroscopy sensor, an optical coherence domain reflectometry sensor, an electrical impedance sensor, a temperature sensor, a pO 2  sensor, a chemical sensor and other sensors useful in identifying tissue. The sensors may take the form of a plurality of optical fibers extending through said needle. A retractable sheath may be disposed around the distal section of the needle to protect the needle when not in use. The sheath retracts when the probe is inserted into tissue and the position of the sheath relative to the needle may be measured to determine the needle&#39;s depth. Systems and methods for tissue identification are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 09/947,171, filedSep. 4, 2001, the entire disclosure of which is incorporated herein byreference.

TECHNICAL FIELD

This invention is directed to tissue identification and in particular,to a multisensor probe for identifying cancerous tissue in vivo.

BACKGROUND

Every week in the United States about 19,000 open surgical breastbiopsies are performed on women. Only about 3000 cancers will be found.Thus, about 85% of the biopsies are unnecessary. This means about 16,000women will needlessly undergo open surgical breast biopsies in the U.S.every week because of the inaccuracy in diagnosing cancerous tissue inthe breast.

Open surgical breast biopsies are highly undesirable because they areinvasive and traumatic to the patient. In a surgical biopsy, thesuspected location of the abnormality would be marked with a thin,hooked guide wire. The surgeon tracts the guide wire to the location ofthe suspected abnormality and the suspect area is excised. The opensurgical biopsy is the most common form of biopsy and is invasive,painful and undesirable to the patient. The open surgical biopsies mayalso leave scar tissue which may obscure the diagnostic ability offuture mammograms, creating a major handicap for the patient.

Another form of biopsy is a large-core needle biopsy (14 gauge needle).The standard core biopsies remove a 1 mm×17 mm core of tissue. The largecore needle biopsy is less invasive than a surgical biopsy but stillremoves an undesirable amount of tissue.

Still another form of biopsy is the stereo tactic fine needle aspirationbiopsy. In this type of biopsy, a small amount of the cells areaspirated for cytological analysis. This procedure is minimallyinvasive. A shortcoming, however, with stereo tactic biopsies is pooraccuracy. The poor accuracy is a result of the small sample size whichmakes accurate cytology difficult.

Another drawback of typical biopsy procedures is the length of timerequired for the laboratory to review and analyze the excised tissuesample. The wait can take, on average, approximately two months from thefirst exam to final diagnosis. Consequently, many women may experienceintense anxiety while waiting for a final determination.

Various methods and devices have been developed to measure physicalcharacteristics of tissue in an effort to distinguish between cancerousand non-cancerous tissue. For example, U.S. Pat. No. 5,303,026 to Stroblet al. (the Strobl patent) describes an apparatus and method forspectroscopic analysis of scattering media such as biological tissue.More specifically, the Strobl patent describes an apparatus and methodfor real-time generation and collection of fluorescence, reflection,scattering, and absorption information from a tissue sample to whichmultiple excitation wavelengths are applied.

U.S. Pat. No. 5,349,954 to Tiemann et al. also describes an instrumentfor characterizing tissue. The instrument includes, amongst other thingsa hollow needle for delivering light from a monochromator through theneedle to a desired tissue region. Mounted in the shaft of the needle isa photodiode having a light sensitive surface facing outward from theshaft for detecting back-scattered light from the tissue region.

U.S. Pat. No. 5,800,350 to Coppleson et al. discloses an apparatus fortissue type recognition. In particular, an apparatus includes a probeconfigured to contact the tissue and subject the tissue to a pluralityof different stimuli such as electrical, light, heat, sound, magneticand to detect plural physical responses to the stimuli. The apparatusalso includes a processor that processes the responses in combination inorder to categorize the tissue. The processing occurs in real-time withan indication of the tissue type (e.g. normal, pre-cancerous/cancerous,or unknown) being provided to an operator of the apparatus.

U.S. Pat. No. 6,109,270 to Mah et al. (the Mah patent) discloses amultimodality instrument for tissue characterization. In oneconfiguration shown in the Mah patent, a system with a multimodalityinstrument for tissue identification includes a computer-controlledmotor driven heuristic probe with a multisensory tip.

Notwithstanding the above, there still exists a need for a convenientand reliable multisensor probe that can provide real time analysis ofmultiple tissue properties. In particular, a multisensor probe andsystem in accordance with the present invention is desirable.

SUMMARY OF THE INVENTION

The present invention includes a multisensor probe for tissueidentification comprising an elongate body having a distal section, adistal tip, and a lumen extending through the elongate body to thedistal tip. The probe further includes an optical scattering andabsorption spectroscopy (OSAS) sensor configured to deliver and receivelight from the distal tip of the elongate body and a position sensorconfigured to measure the depth the distal tip is inserted into thetissue. Suitable position sensors include but are not limited to anoptical sensor, capacitive sensor, or a resistive sensor.

A variation of the present invention includes the multisensor probe asdescribed above wherein the probe further includes a slideable sheathcoaxially disposed over the distal section of the elongate body. Thesheath is retractable from the distal section as the distal section ofthe elongate body is inserted into the tissue. In a variation, theposition sensor is configured to read the position of the sheathrelative to the elongate body.

Another variation of the present invention includes the multisensorprobe as described above wherein the probe further includes anelectrical sensor. The electrical sensor is configured to measureelectrical properties of the tissue. The electrical sensor includes afirst electrically conducting element and a second electricallyconducting element. The first and second electrically conductingelements extend to the distal tip of the elongate body. In a variation,the elongate body is the first conducting element. Suitable materialsfor the first conducting element are stainless steel, aluminum,titanium, gold, silver, and other electrically conducting materials.

Another variation of the present invention includes a multisensor probeas described above wherein the probe further includes a memory devicecapable of storing useful information about the probe.

Another variation of the present invention includes the multisensorprobe described above wherein the probe further includes a switch orpush button for marking a location in the tissue as the distal sectionis inserted into the tissue.

Another variation of the present invention includes the probe asdescribed above wherein the probe further includes additional sensors.In this variation, the multisensor probe additionally includes anoptical coherence domain reflectometry (OCDR) sensor having an opticalfiber extending through the lumen to the distal tip. In anothervariation, the probe further includes a pO₂ sensor and a temperaturesensor. In one variation, the temperature sensor and pO₂ sensor utilizea single fiber optic.

Another variation of the present invention includes the multisensorprobe as described above wherein the probe further includes a form of a18-21 gauge needle. In one variation, the needle is blunt. In anothervariation the needle is sharp. In still another variation the needle iscut and polished at an angle less than 70 degrees and preferably rangingfrom 40 to 60 degrees.

Another variation of the present invention includes a multisensor probefor tissue identification. The probe is connected to a controller via acable. The probe comprises a handle to manipulate the probe and a needlejoined to the handle. A plurality of optical fibers extend from thecontroller, through the cable, through the lumen, to the distal tip ofthe needle. The probe also features a sheath slideably disposed aroundthe distal section of the needle. The sheath is retractable into thehandle when the distal section of the needle is inserted into thetissue. In this variation, the probe includes an optical position sensorcoupled to the sheath to measure position of the retractable sheathrelative to the handle.

Another variation of the present invention includes a multisensor probefor tissue identification. The probe includes a needle having a distaltip and a lumen extending through the needle to the distal tip and aplurality of optical fibers extending from the controller, through thecable, through the lumen, to the distal tip of the needle. In thisvariation, at least two of the plurality of optical fibers are opticalscattering and absorption fiber optics and at least one of the pluralityof optical fibers is an OCDR fiber optic. In a variation, themultisensor probe further comprises a linear optical encoder coupled tothe needle to measure position of the distal tip relative to the tissue.

Another variation of the present invention includes a multisensor probehaving a plurality of sensors configured as shown in any one of FIGS.5A-5H. This variation may also feature a slideable sheath coaxiallydisposed over a distal section of the needle. The sheath is retractablefrom the distal section as the needle is inserted into the tissue. Thisvariation also includes a position sensor configured to read theposition of the sheath relative to the needle.

Another variation of the present invention includes a method foridentifying tissue comprising manually inserting a multisensor probe asrecited in any one of the above described probes.

Still another variation of the present invention is a tissue detectionsystem comprising a multisensor needle comprising a plurality of opticalfibers and a position sensor for determining position of the needlerelative to the tissue. The system also includes a controller configuredto deliver and collect light through the plurality of optical fiberswherein at least one of the fibers is utilized as an OCDR sensor andwherein at least one the optical fibers is utilized for opticalscattering and absorption.

Additional aspects and features of the invention will be set forth inpart in the description which follows, and in part will become apparentto those skilled in the art upon examination of the following or may belearned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are illustrations of a multisensor probe in accordancewith the present invention in an application.

FIG. 1C is a graph of a tissue property versus position for theapplication illustrated in FIGS. 1A and 1B.

FIG. 2A is a partial perspective view of a distal section of amultisensor probe in accordance with the present invention.

FIG. 2B is an end view of the multisensor probe shown in FIG. 2A.

FIG. 3 is a schematic illustration of an optical scattering andabsorption spectroscopy system in accordance with the present invention.

FIG. 4 is a schematic illustration of an OCT system in accordance withthe present invention.

FIGS. 5A-5H are cross sectional views of various multisensor probes inaccordance with the present invention.

FIG. 6 shows an exploded view of a multisensor probe in accordance withthe present invention.

FIG. 7 is a schematic illustration of a position sensor system inaccordance with the present invention.

FIG. 8 is a schematic illustration of a multisensor system in accordancewith the present invention.

FIG. 9 is a schematic illustration of a multisensor system having areference optical fiber.

FIG. 10 is another schematic illustration of a system in accordance withthe present invention.

FIGS. 11A and 11B are measured spectra for normal and malignant tissuerespectively using a probe in accordance with the present invention.

DETAILED DESCRIPTION

The present invention includes a multisensor probe and system foridentifying tissue such as cancerous tissue. The multisensor probe maybe inserted into tissue and continuously measure a plurality ofproperties of the tissue while penetrating the tissue. A processingmodule may be provided to characterize the tissue based on informationincluding but not limited to information received from the probe. Thepresent invention may further include a graphical interface toconveniently display (in real time) results to a doctor while the doctoris inserting the probe into the tissue.

First Embodiment

FIGS. 1A-1C illustrate an embodiment of the present invention in anapplication. Referring to FIG. 1A, a multisensor probe 10 is showninserted in breast tissue 20. The multisensor probe 10 includes a handle14 for manually manipulating the probe and a needle 16 extending fromthe handle. The distal tip of the needle is shown at location A and isdirected towards a suspicious lesion 30. FIG. 1B shows the distal tip ofthe needle within the suspicious lesion 30 at location C.

The probe 10 includes a plurality of sensors to measure tissueproperties which are useful in identifying tissue such as canceroustissue. The sensors may take many forms including, for example, opticalfibers for receiving and transmitting light to and from the probe tip.The probe's position or depth is also measured as the probe 10 isinserted into the tissue 20. These measurements are preferably taken andprocessed continuously and in real time as the probe penetrates thetissue.

FIG. 1C shows graphical output 40 from the procedure illustrated inFIGS. 1A and 1B. In particular, graph 40 shows continuous measurement ofa tissue property as a function of depth (or position). Location Acorresponds to normal tissue; location B corresponds to a lesionboundary or margin; location C corresponds to the center of the lesion30; and location D corresponds to normal tissue distal to lesion 30. Areview of graphical output 40 enables a doctor to diagnose a suspiciouslesion in breast tissue in real time.

FIGS. 2A and 2B show an enlarged view of a distal section of a probe inaccordance with the present invention. Referring to FIG. 2A, probe 100is shown having an elongate body 200 and a lumen 205 extendingtherethrough. A plurality of optical fibers extend through the lumen 205to the distal end of the elongate body. Preferably, the optical fibersare flush with the distal end of the elongate body. It is preferred thatthe fibers or sensors contact or nearly contact the tissue as the probepenetrates tissue to be identified. Hereinafter, sensors include but arenot limited to one or more optical fibers and conductors used forsensing.

The elongate body 200 may be, for example, an 18 to 21 gauge hypodermictype needle. The elongate body may have a length in the range of 0.5 to20 cm., more preferably between 4 and 10 cm. Suitable materials for theelongate body are metals and plastics. A preferred material for theelongate body or needle is stainless steel. Suitable stainless steeltubing is available from Vita Needle, Needham, Mass. However, theelongate body 200 may be comprised of other materials and may have othersizes.

The needle 200 shown in FIG. 2A features a sharp distal end. The distalend is preferably cut and polished after the optical fibers and othersensors are positioned within the needle. Cutting the needle after theoptical fibers are positioned within the needle allows the opticalfibers to be cut flush with the distal tip of the needle. Preferably,the needle end is cut and polished at an angle θ less than 70 degrees,usually between 30 and 70 degrees and most preferably between 40 and 60degrees. Angles less than 70 degrees are preferred because a sharp endmore easily penetrates tissue. However, the distal end of the elongatebody may also be blunt. Blunt tips may be suitable for penetrating softtissue such as brain tissue.

The needle or elongate body may include outer markings which can be reador otherwise detected to determine the position or depth of the probe asit is inserted into tissue. Markings may be read by a camera or atechnician examining the procedure. Suitable markings include but arenot limited to bar code, magnetic codes, resistive codes, and any othercode which can provide position information of a moving device.

FIG. 2B shows an end view of the needle 200 and is illustrative of onesensor configuration in accordance with the present invention. Inparticular, a conductor 250 is centrally positioned in lumen 205 and aplurality of optical fibers 210, 220, 230, 240 are showncircumferencially positioned about the conductor 250. The optical fibersmay be single mode or multimode depending on their use, as will bediscussed further below.

The optical fibers and conductor are preferably bonded within lumen 205using a biocompatible compound such as, for example, F114 epoxymanufactured by TRA-CON, Inc. Bedford, Mass. Filling the lumen with abonding compound prevents tissue from entering the needle tip as theprobe is inserted into tissue.

Alternatively, the sensors may be molded or formed in the probe. Forexample, a biocompatible polymeric material may be coaxially formedaround the individual sensors to form a solid polymer needle having thefiber optics bonded therein.

The optical fibers are also preferably coated with a reflective ormetallic layer that prevents stray light from entering the fibers. Asuitable coating is, for example, a 2000A aluminum coating.

The optical fibers are used to measure tissue properties as the needle200 is inserted into tissue. For example, optical fibers 210, 220, and230 may be used as an optical scattering and absorption spectroscopy(OSAS) sensor and optical fiber 240 may be used as an optical coherencedomain reflectometry (OCDR) sensor. While OCDR optical fiber 240 isshown at the apex 255 of the needle, the present invention is not solimited. For example, a fiber optic used in an OSAS sensor may bepositioned at the apex 255 of the needle. For some applications, it maybe desirable to have one fiber optic or wire positioned at the apex andconsequently extend deeper into the tissue than the other sensors.

Optical Scattering and Absorption Spectroscopy

Optical fibers 210, 220 and 230 may be configured as an opticalscattering and absorption spectroscopy (OSAS) sensor. It is to beunderstood that optical scattering and absorption spectroscopy includesvarious optical measurement techniques which use light scattering andabsorption data to measure a target sample. Non-limiting examples ofOSAS techniques include elastic scattering spectroscopy and inelasticscattering spectroscopy.

FIG. 3 is a schematic illustration of one exemplary optical scatteringand absorption spectroscopy system. In the optical system shown in FIG.3, two optical fibers within the probe needle are present formeasurement of the scattered light: an illumination fiber to deliverlight from one or more light sources to the tissue, and a collectionfiber to receive the scattered photons from the tissue and deliver themto a detector. Light from the fiber at the probe tip enters the tissueand is absorbed and scattered. After multiple scattering events withinthe tissue, a fraction of the incident light enters the collectionfiber, which is located near the illumination fiber. The collected lightis transported by the fiber back to the instrument body where a gratingspectrometer and CCD detector measures the scattered light intensity asa function of wavelength. This measured intensity can then be comparedwith the measured intensity for normal-tissue scattered light. Insteadof using a grating and CCD detector, the scattered light may be measuredwith a series of detectors that use optical filters to separate thedifferent light signals. If the light source includes multiple LED's orlasers then conventional modulation techniques can be employed toseparate the different colors with electronic filters.

Each light source can provide light at a single wavelength (e.g., alaser), a narrow band wavelength (e.g., a LED), or a broad bandwavelength (e.g., a xenon flash lamp) which is believed to bedifferentially absorbed by malignant tissue relative to normal or benigntissue. For example, it has been shown recently that some malignantbreast tumors absorb relatively less light in the spectral range of450-500 nm than normal breast tissue. See, for example, Bigio et al.,Diagnosis Of Breast Cancer Using Elastic-Scattering Spectroscopy.Preliminary Clinical Results, Jour. Biomed. Optics 5, 221-228 (2000) andU.S. Pat. No. 5,303,026. Similarly, differential absorption in theregion of 660 or 940 nm is indicative of deoxygenated hemoglobin, whichis believed to be another indicator of malignancy.

The combination of three optical fibers (210, 220, and 230) as shown inFIG. 2B thus can estimate the optical absorption and scatteringproperties of tissue near the distal tip. In the configuration shown inFIG. 2B, optical fiber 210 may be a multimode optical fiber for emittingand collecting electromagnetic radiation typically in the spectral rangeof 200 nm to 2000 nm. Optical fibers 220 and 230 may also be multimodeoptical fibers for collecting light propagating through the tissue inthe vicinity of the fibers. Fibers that can support multiple modes arepreferred because they are easier to align and are more effective atcollecting and transporting spatially incoherent light.

Note that the probe depicted in FIG. 2A shows OSAS light collectingfiber 230 extending to a point proximal to light collecting fiber 220.The present invention is not so limited and includes extending multiplelight collecting or other optical fibers to identical or differentpoints within the elongate body 200. A suitable configuration, forexample, includes a first light collecting fiber extending to a firstpoint along the needle and a second light collecting fiber extending toa second point wherein the first point is proximal to the second pointfrom 100 to 700 um and more preferably from 100 to 400 um. Likewise, oneor more light collecting fibers may extend to a point equal, proximal ordistal to the tip of a light emitting fiber. When not extending to equallocations, the separation distances can be from 100 to 700 um and morepreferably from 100 to 400 um. The above described fibers thus canextend to (and be flush with) the distal tip of an angled or “sharp”needle as well as a blunt needle. Staggering the optical fibers asdescribed above may also increase the path length of photons travelingto the collecting fiber(s). This creates a longer mean free path and maymake the instrument more sensitive to low concentrations whereabsorption is an important factor.

Note also the collecting fibers 220 and 230 are spaced apart in theradial direction from emitting fiber 210. A suitable (center to center)distance D₁ for light collecting fiber 230 to light emitting fiber 210is from about 175 to 400 um. A suitable (center to center) distance D₂for light collecting fiber 220 to light emitting fiber 210 is about 300to 500 um. Of course, when using a needle having a larger innerdiameter, fibers may be separated greater distances.

Optical Coherence Domain Reflectometry

The multisensor probe 100 of FIG. 2B also features an optical fiber 240which can be used for performing optical coherence domain reflectometry(OCDR). OCDR is an optical technique which can be used to image 1-3 mminto highly scattering tissue. The technique may use a bright, lowcoherence source in conjunction with a Michelson interferometer toaccurately measure backscattered (or transmitted) light as a function ofdepth into the media. A suitable interferometer is, for example, model510 manufactured by Optiphase, Van Nuys, Calif.

A schematic illustration of one OCDR system 400 which may be used withthe present invention is shown in FIG. 4. Optical output from a lowcoherence super luminescent diode 410 is split in a fiber optic coupler420 and directed toward the sample 430 and reference arms of theinterferometer. Reflections from the reference mirror 440 andbackscattered light from the sample are recombined at the splitter andpropagated to the detector 450. Constructive interference at thedetector produces a signal when the sample and reference optical pathlengths are within the longitudinal coherence length of the opticalsource (typically <15 microns). The scanning mirror in the reference armis used to scan the detection point within the sample thereby generatinga single line scan analogous to the A-scan in ultrasound. This singleline scan is sometimes referred to as optical coherence domainreflectometry (OCDR).

The fiber optic 240 used for OCDR is preferably a single mode fiber. Asuitable inner diameter for the fiber optic 240 is 125 microns. An OCDRsensor can provide information about the optical properties of tissuealong a single line defined by the optical fiber 240 cone of opticalemission. The axial spatial resolution along this line is determined bythe spatial coherence of the optical source and is typically less than15 microns. The transverse spatial resolution is determined by the fiberoptic and tissue index of refraction and can vary from five microns nearthe fiber tip to hundreds of microns several mm into the tissue.

In addition to single line scans as described above, a cross-sectionalor optical coherence tomography (OCT) image is produced by scanning theoptical fiber across the sample and collecting an axial scan at eachlocation. OCT techniques are discussed in D. Huang, et al., OpticalCoherence Tomography, Science 254,1178(1991) and Swanson, et al., OpticsLetters 17,151(1992).

Other OCDR and OCT systems which can be used with the present inventionare described in Colston et al., Imaging Of Hard And Soft TissueStructure In The Oral Cavity By Optical Coherence Tomography, Appl.Optics 37, 3582(1998); Sathyam et al., Evaluation Of Optical CoherenceQuantitation Of Analytes In Turbid Media Using Two Wavelengths, AppliedOptics, 38, 2097(1999); and U.S. Pat. Nos. 5,459,570; 6,175,669; and6,179,611.

Electrical Impedance

Probe 100 depicted in FIGS. 2A and 2B additionally includes anelectrical impedance sensor. Electrical impedance sensor in thisembodiment includes electrically conducting elongate body 200 andconductor 250. Suitable materials for the elongate body in thisconfiguration include electrically conducting metals as well aselectrically conducting polymers. The distal tip of the elongate body200 and conductor 250 contact the tissue when the probe is inserted intotissue. The impedance sensor can thus measure various electricalproperties including electrical impedance of the tissue near the probetip.

In a preferred embodiment the electrical impedance is measured atmultiple frequencies that can range from 1 kHz to 4 MHz, and preferablyat 5, 10, 50, 100, 200, 500, 1000 kHz. Electrical impedance is anothermeasurement which is believed to be useful in characterizing tissue,especially when combined with other tissue properties.

In summary, FIGS. 2A and 2B illustrate a multisensor probe 100 having anOSAS sensor, an OCDR sensor, and an electrical impedance sensor inaccordance with the present invention.

Other Sensor Configurations

The sensor configurations of the present invention may vary widely andmay incorporate more or less sensors than those described above.

FIGS. 5A to 5H illustrate cross sectional views of a multisensor probehaving various sensor configurations in accordance with the presentinvention. The configurations shown in these figures are exemplary andnot intended to limit the present invention which is defined by theappended claims.

In each of FIGS. 5A-5H, the needle or elongate body 500circumferentially surrounds a plurality of sensors including OSAS fiberoptics 510; OCDR fiber optics 520; electrical impedance electrodes 530;pO₂ fiber optics 554; combination temperature and pO₂ fiber optics 550;temperature sensors 560; chemical sensors 570.

Referring to FIGS. 5A-5C, the needle includes one or more OSAS fiberoptics 510, one or more OCDR fiber optics 520, and one or moreelectrical conductors 530 for measuring electrical properties such aselectrical impedance. In each of FIGS. 5A-5C, the elongate body 500 iselectrically conducting and also used as one of the conducting elementsfor the impedance sensor. Consequently, the electrical impedance sensorin FIG. 5C includes 3 conducting elements.

The probe illustrated in FIG. 5D is identical to that shown in FIG. 5Cexcept that the elongate body 500 is not a conductor used in sensingelectrical impedance. The elongate body 500 may be made ofnon-electrically conducting material in this configuration such as apolymeric material.

As shown in FIGS. 5E-5G, other sensors may be included within elongatebody 500. The probes shown in FIGS. 5E-5G additionally include a pO₂sensor 540, a temperature/pO₂ sensor 550, and temperature sensor 560respectively.

Temperature and pO₂ measurements are believed to be useful inidentifying abnormal tissue. Malignant tumors are frequentlycharacterized by reduced pO₂ and elevated temperature levels relative toadjacent normal tissue or benign tumors. One convenient all-optical wayto measure pO₂ is by means of fluorescence of a dye that is quenched bythe presence of oxygen. In this approach, the tip of an optical fibercontained within a probe needle is coated with a thin layer of anappropriate fluorescent material. The tip of the fiber is at the tip ofthe needle, and is in direct contact with the tissue. The fluorescentmaterial is excited by means of, for example, a blue LED located in theinstrument body at the proximal end of the fiber and, for example, a redfluorescent light emitted by the material is collected by the fiber andreturned to the proximal end of the fiber where it is spectrally orotherwise separated from the excitation light. The fluorescence lifetimeof the dye depends inversely on the amount of oxygen that diffuses intothe material from the surrounding tissue.

The lifetime can be accurately measured by a technique in which theexcitation light is modulated at a convenient frequency and the phase ofthe fluorescence signal is measured relative to the phase of excitation.See Hoist et al., A Microoptode Array For Fine-Scale Measurements OfOxygen Distribution, Sensors and Actuators B 38-39, 122-129 (1997).Since the phase of the fluorescence signal depends on the lifetime, thephase measurement provides a convenient way to measure P⁰² that is notaffected by coating uniformity or fiber transmission losses. Suitableoxygen sensors which may be incorporated into the present invention are,for example, fiber optic oxygen microsensors manufactured by PreSens,GmbH.

Temperature may also be measured by an all-optical technique that isessentially identical to the method used to measure pO₂. See Klimant etal., Optical Measurement Of Oxygen And Temperature In Microscale:Strategies And Biological Applications, Sensors and Actuators B 00 1-9(1996). In the case of temperature, a different fluorescent materialwhose lifetime is related to temperature is coated on the fiber tip. Aphase-fluorescence detection scheme similar to the phase-fluorescencedetection scheme for detecting oxygen can be used for the temperaturedetection sensor with, perhaps, a different excitation wavelength and adifferent modulation frequency.

The temperature and oxygen sensors may be incorporated into one opticalfiber. This is illustrated in the probe shown in FIG. 5G. The combinedoxygen and temperature sensor 560 could have, for example, a tip coatedwith two dyes: one dye corresponding to the oxygen and one dyecorresponding to the temperature. The other aspects of the temperatureand oxygen detection would be similar to the detection and processingtechniques described above.

The multisensor probes depicted in FIGS. 5E-5G also include an OSASsensor 510, and OCDR sensor 520, and an impedance sensor 530. In FIGS.5E-5G, the elongate body 500 is electrically conducting and used as oneof the conductors in an electrical impedance sensor.

FIG. 5H illustrates yet another sensor configuration having a chemicalsensor. Suitable chemical sensors may include materials (e.g., catalyst)which react to the tissue being penetrated and ion sensors. Themultisensor probe of FIG. 5H also includes an OSAS sensor 510, an OCDRsensor 520, and an impedance sensor 530. The elongate body acts as asecond conductor element for the impedance sensor.

While not shown, other sensors may be incorporated into the elongatebody 500 such as stiffness/elasticity sensors, fluorescence sensors,velocity and accelerometer sensors, pressure transducer or tube sensors,and any other sensor or tool so long as it may fit within the lumen ofthe elongate body.

Second Embodiment

Another multisensor probe 600 in accordance with the present inventionis shown in FIG. 6. The multisensor probe 600 includes a handle 610 andan elongate body or needle 620 extending from the distal end of thehandle. The needle 620 is shown within a slideable sheath 630.

Sheath 630 is configured such that it retracts into the handle 610 whenthe needle is inserted into tissue. When not retracted, the slideablesheath 630 covers the needle 620 to protect against accidental needleexposure. The sheath 630 is urged over the needle using a resilientmember 660 such as a spring. The spring connects to the sheath andapplies a force urging the sheath over the full length of the needle.The force supplied by the resilient member 660, however, is not so greatthat it inhibits manipulation of the needle into the tissue. Theresilient member is thus selected or adjusted to allow the sheath toeasily retract as the needle is inserted into tissue. Suitable materialsfor the sheath include polymeric materials, preferably hard.

The multisensor probe 600 may also include a locking member such as alocking ring 665. The locking ring 665 may be set such that movement ofthe sheath is prevented until the locking ring is rotated. Locking thesheath over the needle is helpful to prevent accidental needle exposure.

The multisensor probe shown in FIG. 6 features a shaft 640 inside thehandle 610. The shaft is affixed within the handle and provides asurface for the sheath to slide over when the sheath retracts into thehandle. The shaft may coaxially surround the fiber optics, conductorsand any other sensors to be used in the multisensor probe. The needle620 is aligned and attached to the shaft such that the needle extendsfrom the handle. The sensors and optics within the shaft continuethrough the shaft and into the needle. The sensor configurations may besimilar to the sensor configurations described above.

The fiber optic, electrical conductors and other sensors may connect toa controller (not shown) which drives the sensors and receives signalsfrom the sensors. The sensor optics and wiring may extend from thehandle to the processor within a flexible cable 650. The flexible cable650 holds and provides protection to the sensors.

The flexible cable includes a proximal end (not shown) and a distal end653. The distal end of the cable 650 is joined to the proximal end ofthe probe handle. In particular, FIG. 6 shows the distal end of thecable joined to the proximal end of shaft 640. While not shown,resilient members or connectors may be deployed at the proximal end ofthe probe handle (i.e., the interface between the cable to the handle)to prevent bending moments from damaging the sensors within the cable.

The proximal end of the cable 650 (not shown) preferably terminates at aoptical connector or coupling. The coupling can be removably connectedto the processor. The connector, for example, may be similar to a fiberoptic ST connector. Thus, the multisensor probe and flexible cable maybe easily connected to the processor prior to a procedure and removedfrom the processor following the procedure. The multisensor probe 600is, in this sense, disposable after a use.

A memory device may also be incorporated into the probe or the connectorsection of cable 650. The memory device could contain information aboutthe probe including calibration parameters. Calibration parameters areuseful for data analysis. In addition, the memory device can be used todetect and prevent multiple uses of the device. A suitable memory devicethat can be integrated with the control electronics is GemWave™ C220available from GEMPLUS.

Position Sensor

The multisensor probe shown in FIG. 6 also includes a position sensor670. The position sensor 670 can be an optical position sensor thatmeasures light reflected off an encoded surface of the sheath 630.Alternatively, the position sensor 670 could be a resistive orcapacitive sensor that couples to a conductor within the sheath 630.

Also, position sensor 670 can be a fiber optic that delivers light froman external light source onto the sheath 630 and returns the reflectedlight back to an external detector. The external light source could havemultiple wavelengths (e.g. red and green); a color-coded pattern on thesheath having at least three different colors would allow for detectinga change in position and direction (e.g. red, green, black).

FIG. 7 is a schematic of an optical position sensing system 700 inaccordance with the present invention. In FIG. 7, two colored lightemitting diodes (LEDs) 760 and 765 are powered by a power supply 770.The power supply 770 may, for example, modulate LEDs 760 and 765 at twodifferent frequencies to allow electronic separation of the two colors.

Light from the LEDs 760 and 765 is combined at fiber optic slitter 775.The light then propagates through a second fiber optic splitter 780 tofiber tip 785 where the light exits. The light emitted from the fibertip 785 reflects off color coded bar 790 and returns through thesplitter 780 to the optical detector 795.

Coded bar or encoder 790 may have various configurations. In onevariation, the color bar 790 has a repeated three-color pattern (e.g.,red, green, blue). As the color bar 790 moves past the fiber tip 785 therelative amplitude of the two colors is decoded to determine the barcolor. By counting the number of bars and the direction the controlelectronics can keep track of the bar position relative to the initialstarting point. The direction is calculated by noting the sequence ofcolor bars. In another variation, color bar 790 has a continuoustransition between two different colors that each correspond to a signalmaximum for each LED color. The absolute position along the bar can bedetermined form the relative intensity of each LED 760 and 765 of theoptical detector 795.

In another optical sensor in accordance with the present invention, onlyone color LED is used and the color bar is selected to produce at leastthree reflected intensity levels. This approach may work with acontinuous and a noncontinuous transition between the color bars.However, this approach may be more susceptible to noise than usingmultiple LEDs.

The above mentioned optical position sensors are described in connectionwith a sheath 630 or like component. When the sheath or other componentis retracted as the needle is inserted, an encoder on the sheath movesrelative to a detection point on the handle of the multisensor probe.However, the present invention is not limited to the above notedposition sensors. Any suitable position sensor may be used andincorporated with the multisensor probe of the present invention. Forexample, the depth of the needle may be measured using a form of rangingtechnology wherein a laser beam is emitted from the handle 610 to thetissue surface. For example, the position of the handle relative to thetissue surface may be determined based on the reflected signal of thelaser beam. Sonic and ultrasonic sensors may also be employed todetermine the position or depth of insertion of the needle.

Another position sensor in accordance with the present invention is toprovide visual marks on the needle. A person watching the procedurecould record the number of marks remaining outside the surface as theneedle is inserted into the tissue. Or, a person may record the numberof marks on the needle covered by tissue as the needle is inserted intothe tissue. A camera may be provided to image the marked needle as it ispushed into tissue. Image analysis would provide depth as a function oftime. However, one disadvantage of position sensors using ranging orimaging techniques is that the user would have to avoid blocking thesensor or camera.

Selected positions may be identified by pressing a button or switch 680of FIG. 6. When activated (e.g., pressed), the button would identify ormark selected positions during insertion of the probe. For example, thephysician may press a switch or button when the needle probe hits asuspect lesion boundary. The selected position is marked and itslocation can be used later by analysis software to distinguish normaltissue from suspicious tissue. Suitable forms of markers include but arenot limited to a lever, button, voice recognition or foot switch.

Tissue Identification Systems

The multisensor probe of the present invention may be used inconjunction with various tissue identification systems. Typically, atissue identification system would include a multisensor needle probe, acontrol module and a flexible cable that connects the probe to thecontrol module. The control module typically includes electromagneticradiation sources, optical detectors, electrical impedance measurementelectronics, and control electronics. Computer software may analyze datacollected during the procedure (e.g., continuously and in real time) andthen provide information about the tissue type.

A tissue identification system 800 in accordance with the presentinvention is illustrated in FIG. 8. The system 800 includes amultisensor probe 810, a cable 820, a measurement package 830, acomputer 840, and various I/O devices 850 connected to the computer.

The measurement package 830 drives various sensors of the probe andmeasures their responses. As discussed above, there may be five sensorsto the measurement package including: an optical scattering andabsorption spectroscopy instrument; an Optical Coherence DomainReflectometry instrument (OCDR); an Oxygen Partial Pressure instrument(pO₂); a temperature measurement instrument (T); an electrical impedancemeasurement instrument (Z). The measurement package may additionallyfeature, but need not to, an Artificial Intelligence—Pattern RecognizerEngine (AIP) 860.

Digital Signal Processors (DSP) 870 can be used to control andpre-process signals which are then fed into the ArtificialIntelligence—Pattern Recognizer Engine (AIP) along with the othersignals. The AIP 860 may be a specialized processor to perform patternmatching on the data received from the other components of theinstrument package. Both artificial neural networks and hierarchicalcluster analysis can be employed to classify the data against other datasets such as data sets generated during, for example, clinical trials.Data can also be compared to normal tissue samples at another locationwithin the patient.

The electronics and processor are preferably configured to takemeasurements continuously and in real time. Preferably, the electronicsand processor are configured to take measurements of the tissue every 1mm for an needle insertion speed of 1 cm/s and more preferably, every0.2 mm. This corresponds to sampling rate of at least about 10 Hz and 50Hz respectively. The above sampling rate provides for determining tissuestructure on a microscopic and macroscopic scale (i.e., 10 micron to 10centimeters).

The Control Computer 840 can provide a convenient human interface anddata management system. It may include, for example, variousinput/output (I/O) devices such as but not limited to: a graphicsdisplay for presenting data in real time, and prompting the operator forinputs; a keyboard for the operator to control the system and inputinformation; a speaker for audible feedback; a microphone for theoperator to annotate readings; a foot switch for the operator to tellthe system to “tag” or mark specific data points; a printer for hardcopy results; a bar code scanner for inputting patient ID; and acommunication port to interface with hospital or laboratory informationsystems and internet.

FIG. 9 shows a schematic of another tissue identification system 900 inaccordance with the present invention. The system 900 includes amultisensor probe 910, a cable 920 that connects the probe to aconnector 930 located on the control module 940. The control module 940includes electromagnetic radiation sources 950 which may be, forexample, multiple lasers or white light sources (e.g. “X-strobe” sold byPerkin Elmer Optoelectronics, Inc. Salem, Mass.).

A fiber optic splitter 960 splits light from sources 950 into anemission fiber 970 and a reference fiber 975A. In this embodiment, areference fiber 975B goes to the probe and returns to a detector 980.The reference fiber 975B preferably extends into the handle of the probeand not into the needle.

By measuring signals of the reference fiber, fluctuations in lightdelivery to the tip of the device due to cable motion may be partlyaccounted for. Fluctuations may occur for a variety of reasons includinglosses through the fiber due to bends in the fiber. Each of the opticalfibers in the probe likely experience similar losses as the referencefiber. This assumption is more accurate if the fibers have a similarnumerical aperture, material properties and are tightly packed andpossibly bonded within the cable. The fibers can be bonded using a softpolymer compound or silicone.

The detection system shown in FIG. 9 features an OSAS sensor and lightis delivered to the sample via fiber 970. Light is collected by twocollection fibers 995, 1010 and is delivered from the connector 930 toseparate optical detectors 990, 1000.

Additionally, light from collection fiber 1010 is split at splitter 1020to deliver light to a fluorescence optical detector 1030. Thefluorescence detector 1030 may be filtered with, for example, notchfilters (available from CVI Laser corp. Albuquerque, N. Mex.) to blockout the excitation laser light.

Optical detectors within the control module can be a gratingspectrometer (e.g. S2000 fiber optic spectrometer, sold by Ocean OpticsInc., Dunedin, Fla.). Alternatively, the light sources may be modulated(e.g. PMA Laser Diode Modules, supplied by Power Technology Inc., LittleRock, Ark.) and electronic filters can be used to measure the opticalsignal at each modulation frequency which is different for eachwavelength. When the light sources are modulated, an optical detectorcan be a silicon photo detector (e.g. PDA55, supplied by ThorLabs Inc.Newton, N.J.).

The tissue identification system 900 may also include an OCDR sensor.The OCDR sensor preferably includes an optical fiber extending to thedistal tip of the needle probe 910. Additionally, the control modulepreferably features an OCDR light source, detector and measurementelectronics 1040 (e.g. OCDR system available from OptiPhase Inc., VanNuys, Calif.). The OCDR fiber 1050 is used to both deliver and collectlight from the needle probe 910.

The tissue identification system 900 shown in FIG. 9 also features anelectrical impedance sensor. The electrical impedance sensor operateswith an electronics module 1060 and may include a three-conductor cable1070 extending to the distal tip of the probe 910.

A main electronics control module 1100 may power and control the variouscomponents and acquire data from the detectors. Analysis software mayprocess the data and displays results on display 1110. A variety ofanalysis techniques can be applied including, for example, neuralnetworks as described in U.S. Pat. No. 6,109,270 to Mah et al. andhierarchical (and nonhierarchical) cluster analysis as described, forexample, in papers by I. J. Bigio, et al, “Diagnosis of breast cancerusing elastic-scattering spectroscopy: preliminary clinical results” inJournal of Biomedical Optics, 5(2), 221-228, (April 2000) andMultivariate Data Analysis, Fifth Edition, by Hair, et al, (1998).

A preferred algorithm includes comparing measurements from normal tissueto measurements of a suspect tissue area. This can be carried out inreal time as the probe is inserted. In particular, tissue proximal tothe target tissue provides a baseline value to the suspect tissue. Forexample, when inserting the probe into the breast to identify suspecttissue, the needle is inserted into the breast in a direction towardsthe suspect tissue. The breast tissue penetrated proximal to the suspecttissue may be used as a baseline to compare to measurements of thesuspect tissue.

Another procedure includes comparing probe measurements of the suspector target tissue to probe measurements taken from another body location.For example, the probe may be inserted into left breast tissue toprovide a baseline. The probe may then be inserted into the right breasthaving the suspect lesion. Comparison of the baseline to the suspecttissue indicates whether the suspect tissue is normal.

Additional information may be used in an analysis to identify thesuspect tissue. Additional information (e.g., patient history) may beused to weight or affect measured values to make the diagnosis moreaccurate. Further, any combination of useful algorithms may be employedwith tissue identification system of the present invention so long asone algorithm does not exclude use of another algorithm. Non limitingexamples of other algorithms include but are not limited to multipleregression analysis, multiple discriminant analysis and multi-variablepattern recognition.

FIG. 10 shows a schematic of another tissue identification system 1200in accordance with the present invention. The system 1200 includes amultisensor probe 1210 coupled to four sensor modules which could behoused in a single control unit module (not shown). In particular, thesystem 1200 includes an OCDR sensor, an optical pO₂ and temperaturesensor, an electrical impedance sensor, and an OSAS sensor. The OCDRsensor, an optical pO₂ and temperature sensor and electrical impedancesensor may be configured similar to the sensors described above.

The OSAS sensor includes a control module 1220, a light emitting fiber1230, and a light collecting fiber 1240. The control module 1220includes electromagnetic radiation sources 1250 which may be, forexample, multiple LEDs (e.g., five different wavelength LEDs), whitelight sources, or lasers. Light emitted from radiation sources 1250 iscoupled into one fiber at first splitter 1260. The light is deliveredfrom first splitter 1260 to a second splitter 1270 where it splits intotwo optical fibers. One fiber leads to reference detector 1290, and onefiber leads to the sample via emitting source fiber 1230. Back scatteredand fluorescence generated at the tissue returns through fiber 1230 andat splitter 1270 couples into a fiber that leads to fluorescencedetector 1280. The light delivered to the fluorescence detector 1280 maybe filtered with, for example, notch filters (available from CVI LaserCorp., Albuquerque, N. Mex.) to block out the excitation laser light.

Light delivered to the sample reflects, transmits and is absorbed by thesample. A collection fiber 1240 collects radiation from the sample.Light collected in the collector fiber 1240 is then delivered to a thirdoptic splitter 1300 which splits the light into two optics. One opticdelivers light to a first detector 1310 which measures, for example, anOSAS signal and one optic delivers light to a second detector 1320 whichincludes a filter to measure fluorescence. The light delivered to thefluorescence detector 1320 may be filtered with, for example, notchfilters (available from CVI Laser corp. Albuquerque, N. Mex.) to blockout the excitation laser light.

Applications

Applications for the present invention can vary widely. For example, thepresent invention may be used to detect cancerous tissue in the breast.The multisensor probe of the present invention may also be used tocharacterize other types of abnormalities found in other locations ofthe body. The probe of the present invention may be used in vivo asdescribed above or alternatively, the probe may be used to identifytissue in vitro. Preferably, the probe of the present invention isconfigured to measure tissue properties in real-time and continuously asthe probe tip is inserted into a tissue sample. The probe of the presentinvention is thus effective beneath the surface of an organ or tissuesample (e.g., subcutaneously) and is not limited to merely contacting asurface or surface area of tissue to be diagnosed. While penetrating thetissue sample, signals from the multiple sensors of the probe areimmediately processed to quickly diagnosis, identify or characterize thetissue.

The device of the present invention may also be used in combination withother medical devices. For example, the needle of the multisensor probemay be inserted through a cannula or other tubular structure used inmedical procedures.

The present invention also includes a method and device for determiningthe approximate size of an abnormality such as a tumor. The size of thetumor could be calculated based on marking the boundaries of thesuspicious lesion as discussed above. The distance between the first andsecond boundary could be stored and used in an algorithm to determine anapproximate size of the suspicious lesion.

EXAMPLES

A multisensor probe in accordance with the present invention was builtand tested. The probe featured a needle, a handle for manipulating thehandle, an OSAS sensor, and OCDR sensor, and an impedance sensor. TheOSAS sensor included a source fiber and two collection fibers. The OCDRsensor included a single mode fiber. The electrical impedance sensorincluded a central conductor as one electrode and the outer needle wallas the second electrode.

A xenon flash lamp was used as a light source for the test probe. FIGS.11A and 11B show the spectrum of light collected by two OSAS fibersduring in-vitro testing for normal and malignant tissue respectively.The line or “signature” represented by “channel 2” represents lightcollected from one optical fiber and the line represented by “channel 3”represents light collected from another optical fiber. The “channel 2”optical fiber was closer (center to center) to the light emitting fiberthan the “channel 3” fiber.

Amplitude as a function of lambda (nm) is plotted in FIGS. 11A and 11B.As evidenced by the data, significant differences in tissue opticalproperties between normal and malignant tissue are observed. Inparticular, data corresponding to the malignant tissue (FIG. 11B)differs significantly from the data corresponding to the normal tissue(FIG. 11A). The differences include but are not limited to the amplitudeas well as the slope of the amplitude. Further, the data lines differ atvarious wavelength ranges such as, for example, from 450 to 550 nm.Accordingly, the test probe of the present invention may be used todetect or differentiate malignant tissue from normal tissue.

All publications, patent applications, patents, and other referencesmentioned hereinafter are incorporated by reference in their entirety.To the extent there is a conflict in a meaning of a term, or otherwise,the present application will control.

All of the features disclosed in the specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive. Each feature disclosed, in this specification(including any accompanying claims, abstract and drawings), may bereplaced by alternative features serving the same, equivalent or similarpurpose, unless expressly stated otherwise. Thus, unless expresslystated otherwise, each feature disclosed is one example only of ageneric series of equivalent or similar features. The invention is notrestricted to the details of the foregoing embodiments. The inventionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

1. A multisensor probe for tissue identification comprising: an elongate body having a distal section, a distal tip, and a lumen extending through said elongate body to said distal tip; an optical scattering and absorption spectroscopy sensor configured to deliver and receive light from said distal tip of said elongate body; and a position sensor incorporated into said probe and configured to measure the depth said distal tip is inserted into said tissue.
 2. The multisensor probe of claim 1 further comprising a slideable sheath coaxially disposed over the distal section of said probe, said sheath being retractable from said distal section as said distal section of said elongate body is inserted into said tissue.
 3. The multisensor probe of claim 1 wherein said position sensor is selected from the group consisting of an optical sensor, capacitive sensor, resistive sensor, laser ranging, sonic sensor, and a camera.
 4. The multisensor probe of claim 1 wherein said position sensor is an optical encoder.
 5. The multisensor probe of claim 2 wherein the position sensor is configured to read the position of said sheath relative to said elongate body.
 6. The multisensor probe of claim 1 further comprising a handle for manipulating said multisensor probe.
 7. The multisensor probe of claim 1 further comprising a marking switch to identify a location in said tissue as said distal section is inserted into said tissue.
 8. The multisensor probe of claim 2 further comprising a spring to urge the sheath over the distal section such that when said probe is not in use, said sheath encloses said distal section of said elongate body.
 9. The multisensor probe of claim 1 further comprising a electrical sensor for measuring electrical properties of said tissue.
 10. The multisensor probe of claim 9 wherein the electrical sensor comprises a first electrically conducting element and a second electrically conducting element, said first and second electrically conducting elements extending to the distal tip of said elongate body.
 11. The multisensor probe according to claim 10 wherein said first electrically conductive element is said elongate body.
 12. The multisensor probe of claim 11 wherein the elongate body is a material selected from the group consisting of stainless steel, aluminum, titanium, gold, and silver.
 13. The multisensor probe of claim 12 wherein said second electrically conductive element extends through said lumen.
 14. The multisensor probe of claim 1 further comprising a memory device capable of storing useful information about the probe.
 15. The multisensor probe of claim 1 further comprising an OCDR sensor, said OCDR sensor comprising an optical fiber extending through said lumen to said distal tip.
 16. The multisensor probe of claim 15 wherein the optical scattering and absorption spectroscopy sensor includes at least three optical fibers extending through said lumen to said distal tip.
 17. The multisensor probe of claim 16 wherein the elongate body has an outer diameter less than or equal to that of a 18 gauge needle.
 18. The multisensor probe of claim 1 further comprising a P⁰² sensor.
 19. The multisensor probe of claim 18 further comprising a temperature sensor.
 20. The multisensor probe of claim 19 wherein the temperature sensor and pO₂ sensor utilize a single fiber optic.
 21. The multisensor probe of claim 1 wherein the distal tip of the elongate body is sharp.
 22. The multisensor probe of claim 21 wherein the distal tip defines a plane and the plane forms an angle with an axis of said elongate body, said angle ranging from 30 to 70 degrees.
 23. A multisensor probe for tissue identification, said probe connectable to a controller via a cable, said probe comprising: a needle having a distal tip and a lumen extending through said needle to said distal tip; and a plurality of optical fibers extending from said controller, through said cable, through said lumen, to said distal tip of said needle when said probe is connected to said controller, wherein at least two of said plurality of optical fibers are optical scattering and absorption spectroscopy fiber optics and wherein at least one of said plurality of optical fibers is an OCDR fiber optic, and wherein a position sensor is incorporated into said probe, said position sensor adapted to measure depth the needle is inserted into the tissue.
 24. The multisensor probe of claim 23 wherein the position sensor is a sensor selected from the group consisting of a resistive sensor and a linear optical encoder.
 25. The multisensor probe of claim 23 having a conducting element extending through said lumen.
 26. The multisensor probe of claim 23 further comprising a slideable sheath coaxially disposed over a distal section of said needle, said sheath being retractable from said distal section as said needle is inserted into said tissue.
 27. The multisensor probe of claim 26 wherein the position sensor is configured to read the position of said sheath relative to said needle.
 28. A method for identifying tissue comprising: manually inserting a multisensor probe as recited in claim 1 into said tissue.
 29. A tissue detection system comprising: a probe, said probe comprising a multisensor needle comprising a plurality of optical fibers, said probe further comprising a position sensor adapted to sense depth of the needle into said tissue; and a controller configured to deliver and collect light through said plurality of optical fibers wherein at least one of said fibers is utilized as an OCDR sensor configured for measuring backscattered and reflected light as a function of depth into the tissue and wherein at least one said optical fibers is utilized for optical scattering and absorption.
 30. The system of claim 29 further comprising at least one electrode for sensing electrical information about the tissue.
 31. The system of claim 29 further comprising a sheath which retracts when the needle is inserted into said tissue.
 32. The system of claim 31 wherein said position sensor measures said position of said sheath relative to said needle.
 33. A multisensor probe for tissue identification, said probe connected to a controller via a cable, said probe comprising: a handle to manipulate said probe; a needle joined to said handle, said needle having a distal section, a distal tip and a lumen extending through said needle to said distal tip; a plurality of optical fibers extending from said controller, through said cable, through said lumen, to said distal tip of said needle; a sheath slideably disposed around said distal section of said needle, said sheath being retractable into said handle when said distal section of said needle is inserted into said tissue; and an optical position sensor coupled to said sheath to measure position of said retractable sheath relative to said handle, said position corresponding to the depth of insertion of said needle into said tissue.
 34. The multisensor probe of claim 23 comprising a first light collecting fiber extending to a first point and a second light collecting fiber extending to second point wherein each of said first collecting fiber and second light collecting fiber is useful in optical scattering and absorption spectroscopy and wherein said first point is proximal to said second point.
 35. The multisensor probe of claim 34 wherein said first point is proximal to said second point from 100 to 700 um.
 36. The multisensor probe of claim 23 comprising a light collecting fiber having a center and a light emitting fiber having a center wherein said center of said light collecting fiber is separated from said center of said light emitting fiber by 175 to 500 um.
 37. The multisensor probe of claim 36 wherein said center of said light collecting fiber is separated from said center of said light emitting fiber by 300 to 500 um.
 38. The multisensor probe of claim 10 wherein said elongate body is made of a conducting polymer.
 39. The multisensor probe of claim 14 wherein said memory device is configured to detect whether said probe has been previously used in a tissue identification procedure.
 40. The multisensor probe of claim 39 wherein said memory device is configured to prevent said probe from being used more than once.
 41. The multisensor probe of claim 1 wherein said position sensor is a resistive sensor.
 42. The multisensor probe of claim 1 wherein said position sensor is configured to detect movement of a component of the probe that is displaced as said distal tip is inserted into said tissue.
 43. The multisensor probe of claim 16 wherein said optical fibers include at least one multimode fiber and at least one single mode fiber.
 44. A multisensor probe for tissue identification comprising: a handle; an elongate body extending from the handle, said elongate body having a distal section, a distal tip, and a lumen extending through said elongate body to said distal tip; an optical scattering and absorption spectroscopy sensor configured to deliver and receive light from said distal tip of said elongate body; and a position sensor incorporated into said handle and configured to measure the depth said distal tip is inserted into said tissue.
 45. The multisensor probe of claim 1, wherein the position sensor is configured to generate a measurement of the depth said distal tip is inserted into said tissue.
 46. The multisensor probe of claim 1, wherein the position sensor comprises an electronic position sensor.
 47. The multisensor probe of claim 23, wherein the position sensor is configured to generate a measurement of the depth said distal tip is inserted into said tissue.
 48. The multisensor probe of claim 23, wherein the position sensor comprises an electronic position sensor.
 49. The method of claim 28, further comprising electronically measuring the depth the distal tip of the probe is inserted into the tissue.
 50. The multisensor probe of claim 44, wherein the position sensor is adapted to generate a measurement of the depth said distal tip is inserted into said tissue.
 51. The multisensor probe of claim 44, wherein the position sensor comprises an electronic position sensor. 